Foam compositions are useful in a number of product categories, including skin and hair care products and cleaning products, such as hand soap, shampoo, body soap, hair mousse, shaving foam and kitchen cleanser. For example, foam compositions can provide improved spreadability and distribution of the ingredients in the hair or on the skin relative to gel, lotion, or cream forms of such compositions, particularly when a low level of the composition is intended to be used. In addition, there has been significant improvement in the efficacy of skin and hair care products, notably through the use of polymers. The use of such polymers can result in a foamable liquid having a higher viscosity, which, as is described below, can effect the quality and the ease of dispensing of the foam made therefrom.
In general, a foam is generated by mixing a foamable liquid and a gas. Dispensers and dispensing nozzles for forming and dispensing a foam from a foamable liquid are well known. In the case of pump foam and squeeze foam dispensers (also called pump foamers and squeeze foamers, respectively), the gas is normally air, while in the case of aerosol dispensers, the gas is liquefied propane gas or other liquid propellant. (Hereinafter the gas will be referred to generally as air unless otherwise specified.) The mixture of foamable liquid and air approaching and entering the foam dispensing nozzle, which houses the foam refining means, can be a simple mixture or can itself be substantially a foam. Although the liquid and air mixture can be partially separated into large bubbles of air and/or streams of liquid, it is preferred that the bubble-containing foam mixture be substantially intermixed and more uniformly sized prior to it passing through the foam refining means and forming a final foam. The uniformity of the size of the bubbles of a foam can be improved by using a foam refining means that has uniform passageway size and orientation.
As described, for example, in U.S. Pat. No. 3,709,437, issued to Wright on Jan. 9, 1973, U.S. Pat. No. 3,937,364, issued to Wright on Feb. 10, 1976, U.S. Pat. No, 4,156,505, issued to Bennett on May 29, 1979, and U.S. Pat. No. 4,880,161, issued to Wright on Nov. 14, 1989, such dispensers and dispensing nozzles form a foam by mixing a foamable liquid and air, and discharging the resulting foam.
Foam dispensing nozzles and dispensers have used a variety of means and methods for containing the liquid and the air, and for bringing the liquid and air together to be mixed into a foam, including aerosol canisters, deformable reservoirs and foam pumps which are squeezed or actuated by the user to express the foamable liquid and air to a mixing chamber. Also known are such dispensing nozzles and dispensers which employ one or more means, such as a meshed screen or porous frit, to further refine the mixture which has been formed once the foamable liquid and air have been combined with one another.
In alternative embodiments, the foaming compositions of the present invention are also contemplated to be deliverable from other types of dispensers having a foam dispensing nozzle described above. Examples of alternative dispensers are conventional squeeze foamer packages which can be fitted with the foam dispensing nozzle of the present invention. Prior art squeeze roamers comprise a deformable container or reservoir for containing the liquid product to be dispensed and a foamer head, nozzle, or other foam producing means. The foamer product is produced from these squeeze foamer devices by squeezing the container with the hand to force the contained liquid product through the foamer head, nozzle, or other foam producing means. However, the conventional foamer heads, nozzles, and other foam producing means of current squeeze foamers are unable to deliver the foamable compositions of the present invention as foams having the highly desirable characteristics described herein.
Squeeze foamers suitable for use herein can be provided by fitting conventional, deformable squeeze foamer containers or reservoirs with the foam dispensing nozzles of the present invention. Conventional, squeeze foamer containers and reservoirs useful for fitting with the foam dispensing nozzles of the present invention are described in the following patents, all of which are hereby incorporated by reference in their entirety: U.S. Pat. No. 3,709,437, to Wright, issued on Jan. 9, 1973; U.S. Pat. No. 3,937,364, to Wright, issued on Feb. 10, 1976; U.S. Pat. No. 4,022,351, to Wright, issued on May 10, 1977; U.S. Pat. No. 4,147,306, to Bennett, issued on Apr. 3, 1979; U.S. Pat. No. 4,184,615, to Wright, issued on Jan. 22, 1980; U.S. Pat. No. 4,598,862, to Rice, issued on Jul. 8, 1986; U.S. Pat. No. 4,615,467, to Grogan et al., issued on Oct. 7, 1986; and French Pat. No. 2,604,622, to Verhulst, published on Apr. 8, 1988.
Pressurized aerosol delivery systems are also well-known in the art and generally comprise a reservoir (usually a metal canister) for containing the composition to be dispensed and the propellant (usually a gas or liquefied gas) for dispensing the composition, a dip tube, and a nozzle. Aerosol delivery systems can be prepared by fitting a canister and dip tube with a nozzle of the present invention and charging the delivery system with the composition to be delivered and a suitable propellant. The level of propellant, based on the total weight of the cleansing composition plus the propellant, is such that the propellant comprises from about 20% to about 90%, preferably from about 25% to about 80%, and more preferably from about 30% to about 50%, of the total composition. Examples of propellants useful herein include those selected from the group consisting of chlorinated, fluorinated, and chlorofluorinated lower molecular weight hydrocarbons (nonlimiting examples of which are the freons); nitrous oxide; carbon dioxide; butane; propane; and mixtures thereof.
A conventional pump foam dispenser generally comprises a reservoir including an opening and adapted to contain a quantity of a foamable liquid, and a manually-actuable pump means adapted to fit partially inside of and sealably attached to the opening of the reservoir. The sealable attachment of the pump means normally comprises a set of mating threads on the housing of the pump means and on the opening of the reservoir. In addition to the pump for supplying the foamable liquid from the reservoir and the air, the pump means normally also includes a mixing chamber for mixing the foamable liquid and the air into a foam mixture and a flow regulating orifice through which the foam mixture passes. The pump means is also connected downstream with the dispensing nozzle for further refining and dispensing the resultant foam.
In the case of most manually-actuable pump foamers, the actuation by the user supplies both the foamable liquid and the air to the mixing chamber. The foamable liquid is usually dispensed by the pump to the mixing chamber at a fixed volume with each full stroke of the pump. A fixed volume of air can also be supplied to the mixing chamber by means of the same or a separate pump. Alternatively, a variable volume of air can be drawn into the mixing chamber by means of check valves and venturi suction created by the flow of the foamable liquid into the mixing chamber.
A preferred prior art pump foam dispenser is shown in Japanese Laid-Open Utility Model No. Hei 3-7963 (Daiwa Can Co., Ltd.). This publication discloses a dual chamber pump foam dispenser wherein the foamable liquid and the air are separately but simultaneously pumped to a mixing chamber, thereby providing a consistent ratio and quantity of liquid and air with each full actuation of the pump.
The foamable liquid and the air are mixed as they pass through the mixing chamber and are discharged through a flow restricting orifice in the mixing chamber. The flow restricting orifice exerts back pressure against the flow of the resulting foam from the mixing chamber, which generates turbulence and causes mixing inside the mixing chamber. The back pressure created by the flow regulating orifice also causes, to some extent, resistance to the manual actuation of the pump means, thereby providing the user who is applying a force to the actuating means with a sense of or feel of the rate of dispensing of the foam mixture. The flow regulating orifice can range in size, depending upon such factors as the intended amount of foamable liquid and air to be dispensed, the viscosity of the foamable liquid, etc. Typically, the flow regulating orifice is from about 1 mm to about 3 mm in diameter. The foam discharged from the foam regulating orifice, which passes out of the pump means through a pump discharge tube is called intermediate foam.
From the pump discharge tube, the intermediate foam typically enters into a foam dispensing nozzle, which is typically in the form of a conduit. The foam is at this point comprised of bubbles having a wide range of sizes. This foam typically passes through at least one homogenizing or refining means in the conduit before exiting the foam dispensing nozzle as a final foam ready for use by the user. Such refining means is typically a screen of about standard mesh size 100 or more. A screen is typically characterized by its mesh size, which is the number of openings (also called passageways) per linear inch counting from the center of any wire to a point exactly 1 inch distant. Equivalently, a screen can also be characterized by either its opening size and diameter of the wires, both of them specified in units of mils (thousandths of an inch) or mm, or its opening size, specified in units of mils (thousandths of an inch) or mm and its percentage open area. Finally, the total area of a screen normal to the flow of the foam consists of two parts: (1) the open area of the screen (also called the flow area), which is the area of all openings of the screen, and the area of the screen covered by all wires. Known conventional foam dispensing nozzles typically use a refining screen having a total area, normal to the flow of the mixture, of about 0.2 cm.sup.2 to about 0.6 cm.sup.2.
Some prior art workers have tried to further improve the quality of the foam mixture exiting the primary refining screen by passing it through a second refining screen (also called the final or discharge screen) positioned nearer to the discharge of the foam dispensing nozzle, as is shown in FIG. 2 of U.S. Pat. No. 4,932,567, Tanabe et al., issued on Jun. 12, 1990. Other examples of such conventional pump foam dispensers are disclosed in Japanese Utility Model Nos. Showa 60-24426 and Showa 63-21119, and U.S. Pat. No. 4,509,661, to Sugizaki et al., issued on Apr. 9, 1985. The typical total area of the discharge screens in such conventional foam dispensing nozzles, as measured normal to the flow of the foam, is about 0.2 cm.sup.2 to 0.4 cm.sup.2.
These dispensing nozzles and dispensers work satisfactorily, but they are not completely effective in dispensing a foam exhibiting characteristics which are generally preferred to users. Accordingly, there remains a need to improve the quality of foams generated from various types of foamable liquids. In particular, conventional pump or squeeze foamers are not well suited for forming thick, stable (also called persistent) and homogeneous foams from a thicker, more viscous foamable liquid especially one having a viscosity at the conditions of usage of about 50 centipoise (hereinafter referred to as "cps") or more. Although aerosol propellants and aerosol dispensers can be used with some success with such viscous foamable liquids, there is currently a keen interest in reducing or avoiding the use of such aerosol propellants, and dispensers which rely upon them, from an environmental standpoint.